This invention relates generally to a dispensing pump wherein the pumping action is effected through deformation of a resiliently flexible bulbous diaphragm. More particularly, the diaphragm is provided with annular skirts for simultaneously opening and covering discharge and inlet ports upon deformation of the diaphragm, and for opening and covering a vent port in response to a given fluid pressure within the vent port.
U.S. Pat. No. 3,785,532, dated Jan. 15, 1974 and commonly owned herewith, discloses a dispensing pump of the press bulb type having inlet and discharge valves for respectively controlling the closing and opening of inlet and discharge passages upon axial deformation of a bulbous diaphragm. As is typical for this type of dispensing pump, as well as for dispensing pumps disclosed in U.S. Pat. Nos. 2,815,890, 2,853,210, and 3,102,489, after the pump chamber is filled with the product to be dispensed, the product is discharged from and subsequently refills the chamber each time the diaphragm is depressed and released. Further disclosed in U.S. Pat. No. 3,785,532 is a vent for the container which communicates with the atmosphere when dispensing the product. However, in order to dispense the product, a discharge spout and an outer member must be relatively rotated so as to bring discharge port segments of the outer member and an inner member into registry. A groove and a vent are likewise placed in communication with one another during such relative rotation so as to permit the venting of air from the atmosphere into the container interior during the dispensing operation.
Despite the advantages over the prior art arrangements with the use of the dispensing pump set forth in U.S. Pat. No. 3,785,532, relative rotation of parts thereof is required prior to dispensing for the purpose of not only registering discharge port segments but also for registering vent port segments necessary for the dispensing operation. Therefore, the number of parts required to be formed and assembled in carrying out such an operation results in a more costly and complex dispensing pump arrangement.